For users of vehicles capable of travelling on the surface of the earth (for example, cars or ships) it is attractive to have topographic information concerning the surroundings at their disposal, in visual form.
The invention relates to a method for the perspective display of a part of a topographic map by selecting, in dependence on a position of a vehicle, topographic information from a data structure, where under the influence of a coordinate transformation the display takes place according to a principal viewing direction which encloses an acute angle with respect to the surface of the earth. The invention also relates to a device suitable for performing such a method. A method of this kind is known from the French patent application No. 2610752. This application discloses a method where a representation of a not necessarily flat terrain, stored in a data structure as a network of nodes, is transposed into a surface extending through the constituent nodes by interpolation, said surface being projected onto an auxiliary plane. A map or photograph of the terrain, containing colour information, is superposed on the surface and projected onto the auxiliary plane. A perspective image of the terrain is thus obtained, "dressed up" with the colour information from the map or photograph. This supplies, for example, a pilot with information about the terrain he is flying over. It is a drawback of such a method that the supply of information to a user is always limited to the image he would personally perceive in ideal circumstances.